The present invention addresses problems associated with regenerating maxillofacial bone mass to treat congenital or functional masticatory deficiencies. Conventionally, in order to overcome masticatory deficiencies, a patient with marginal bone mass is first treated with a surgical bone graft. Bone grafting techniques range from a harvested autogenous onlay graft to a synthetic hydroxyapatite bone mixture used to pack and build up a surgical site. Once the graft has healed, a second surgery is performed to insert the appropriate length endosseous dental implant and to provide masticatory function.
The process of bone grafting to regenerate bone mass has suffered from limited results. In many cases, at the time for surgical insertion of the endosseous dental implant, the grafting mass has significantly or completely resorbed away. One reason for the loss of this grafting material is the body's requirement for an applied stress to stimulate and maintain bone mass. Furthermore, as documented cases have shown, it is not uncommon for the filler material to migrate from the surgical site. This migration and degradation of the graft material minimizes the benefit of the procedure. These undesired results combined with the morbidity of the harvested area demonstrate the need for an alternative surgical procedure. In addition, these conventional multiple surgical procedures require a greater investment of time, money and available grafting materials than is desirable.
In U.S. Pat. No. 5,889,940, assigned to the assignee of the present invention, the subject matter of which is incorporated herein by this reference, a maxillofacial anchoring and distraction system for bone lengthening and distracting osteogenesis is disclosed and claimed comprising an internally threaded base plug for placement in a corticotomy that acts as a base plate for resisting and translating the distraction force, an internally and externally threaded anchoring screw body for locking into the coronal portion of the corticotomy and a defined length distraction jack screw for applying the distraction force. Upon preparation of an osteotomy, the base plug and anchoring screw body are placed therein and the distraction jack screw is inserted. The distraction screw is advanced a selected amount on a periodic basis applying a distraction force on the base plug. When the desired amount of distraction has been achieved, the jack screw is removed and replaced with a healing screw. After a suitable healing period, the healing screw is removed followed by the anchoring screw body and the base plug. A suitable endosseous dental implant is then inserted in a conventional manner. Although the above described apparatus and procedures are very effective, there is a need or desire to provide enhancements in certain case situations. In one such case, the situation relates to the lack of sufficient bone height and/or stability to accommodate the components described in the above referenced patent. In another such case, there is adequate bone height but distraction is necessary to translate the coronal aspect of the implant to its required axial location.